class Screen(object):
    # width和height属性，以及一个只读属性resolution
    
    @property
    def width(self):
        return self._width

    @width.setter
    def width(self, value):
        self._width = value

    @property
    def height(self):
        return self._height

    @height.setter
    def height(self, value):
        self._height = value

    @property
    def resolution(self):
        return self._width*self._height



# 测试:
s = Screen()
s.width = 1024
s.height = 768

# 只读变量
# s.resolution = 234

# print('resolution =', s.resolution)
# if s.resolution == 786432:
#     print('测试通过!')
# else:
#     print('测试失败!')